This is my entry for the #3DPNSpeakerCover contest!
This design is though and developed specifically with FDM technology in mind, but other 3D printing process could work too.
The idea that drives this design is based on "maximum protection" while the speaker is off while allowing a great "sound flow" when the speaker is on. This is achieved by a print in place mechanism that allow the cover to open and close by simply rotating the center piece of the cover itself. You can find an animation here: https://youtu.be/RlJpd2h9WQA
The design is divided in two pieces to completely avoid any support structure.
The first layer needs to be well tuned to avoid "elephant foot" effect, nonetheless chamfers are present to reduce this effect. A layer height of 0.15mm or less is suggested to achieve better tolerances. Minimum clearance between moving parts is 0.3mm (guide rail and internal guide surfaces) and then goes up to 0.4mm and above. Before starting this print, be sure that your machine can handle it ;).
To (hopefully) reduce any rattling noise due to vibrations, end stops are integrated into guide rails to lock in place the mechanism.
Have fun!